int32_t nextX0, x0, x1, nextSq1;
float y0;

nextX0 = x0 = x1 = 0;
nextSq1 = 1 << 22;
y0 = 0;

int32_t outGain = param_OutGain << 3;
const int32_t *pIn = inlet_in;
int32_t *pOut = outlet_out - 1;
while (pOut < outlet_out + BUFSIZE - 1) {
  float r;
  float y1 = y0;
  y0 = arm::vsqrtf(arm::q_to_float(nextSq1, 22));
  nextX0 = ___SMMUL(param_InGain, *pIn) << 7;
  nextSq1 = ___SMMLA(nextX0, nextX0, 1 << 22);
  int32_t x1_x0 = x1 - x0;
  if (abs(x1_x0) > (1 << 17)) {
    r = y1 - y0;
    r /= arm::q_to_float(x1_x0, 27);
  } else {
    r = arm::q_to_float(x0, 27) / y0;
  }
  x1 = x0;
  x0 = nextX0;
  pIn++;
  pOut++;
  *pOut = ___SMMUL(outGain, arm::float_to_q(r, 30));
}